Radio apparatus and method of manufacture



Jan. 17, 1939. L. A. HYLAND RADIO APPARATUS AND METHOD OF MANUFACTURE Filed July 12, 1935 Patented Jan. 17, 1939 RADIO APPARATUS AND METHOD OF MANUFACTURE Lawrence A. Hyland, Washington, D. 0., assignor,

by mesne assignments, to Bendix Radio Corporation, New York, N. Y., a corporation of Delaware Application July 12, 1935, Serial No. 31,083

Claims. (01. 250-33) This invention relates to radio apparatus. More particularly this invention relates to radio antennas of the electrostatically shielded loop type and the method of producing such antennas.

insulator assembly so that one end of each of the tubular members presses into the grommet while the two other ends coincide roughly with the location of the unjoined ends of the conductors.

An object of this invention is to provide a loop A fixture is employed then to press the tubular 5 antenna housing of a substantially doughnutmembers together which places the rubber ring shape, formed out of substantially straight memor grommet under compression making a waterber bent into shape and out into two substantight joint at that point. The conductors are tially symmetrically shaped units into which the then joined together in such a manner as to pro- 7 antenna conductors are positioned. vide a continuous circuit having the required 10 Another object of this invention is to provide number of turns in series, shunt or series shunt,

a method of making loop antennas of the doughas may be desired. A fitting is then placed in nut-shaped-electrostatically shielded type in a suitable space previously formed in the tubular which the antenna conductors are positioned members. The members are welded to each within the shield which is formed in two symother and to the fitting after which the fixture 15 metrical sections having one pair of the abutting is removed. he completed s de p faces or adjacent ends thereof welded while the tenna is then ready for installation on any suitother adjacent ends are pressed into a grommet ab e mounting mechanism.

of insulating t i l, Other features of this invention will be appar- Another object of this invention is toprovide ent from the following description and the claims an electrostatically shielded loop antenna having when read with the drawing in which briefly,

a hi ld housing d of t substantially Fig. 1 shows a bent semicircular tubular shieldsymmetrical sections in which a plurality of coning s ng in which the loop conductor-insulaductors are symmetrically disposed with relation tor assembly is inserted; 2 shows a detail to the shielding housing. View of the conductors threaded through spacers;

A further object of this invention is to prog. 3 ShOWS an enlarged View Of one of the vide a shielded loop antenna in which the shield pac s; 4 lustrates the manner in which is d f t ti formed i to predeterthe conductors are threaded through the shield mined shape, one end f h ti being members; Fig. 5 shows the conductors threaded pressed into an insulating and watertight memthrough the shield and the bottom ends of the her d t th tw d joined t ea h th r shield joined and Fig. 6 illustrates the assembled and to an attachment fitting. loop.

In accordance with this invention I provide r ng to Fig. 1 of the drawing in det a loop antenna of the shielded type which is more e erenc numeral l designates a tubular memrugged, has greater electrical efficiency, and is her of aluminum, copper or the like, formed into capable of more economical manufacture than a miircul r s p m m y be n from loop antennas made in accordance with convene St a ht piec o tu Where desired, the tional practice. tubing i may be coated inside thereof with a rel- My method i t of steps Such as th fo1 atively heavy oxide insulating layer and in cases lowing: A tubular member of metallic material, Where aluminum s emp y d in fabricating this 49 such as copper, aluminum, brass and the like, is tube this Coating y be applied chemically or filled with material such as rosin and then bent electrically by nv n l pr esses. The outer into substantially a semi-circular shape. The Sulfa-Ce 0f the tube y a so be oXidiZed With rosin is then removed. A plurality of conductors a relatively thick Coating um num oxide, and such as copper wire or similar material and a one or both of the two halves of the loop shield I plurality of insulating members are assembled en dyed W suitable y and Coloring ted formed int th loo tructure, one of the rials which are readily absorbed by the aluminum insulating members being joined with a rubber oxide. The purpose of applying this coloring maring or grommet which is to be adjacent to two terial is to enable the operator, manipulating the ends of the tubular housing. The wires and inloop to dete the p y of the p When 50 sulators are maintained in spaced position with respect to one another after assembly by means of crimping or soldering and by fitting of the insulators within the housing. Two of the tubular members are then placed over the conductor it is employed in direction finders of the unilateral type.

The tube l is cut out at 3 to accommodate the mounting fitting. A plurality of conductors 4, of a suitable length are threaded through the holes a of the spacer insulators 5. These conductors are preferably sufficiently resilient to maintain their form and prevent undesired kinks from forming therein. The conductor-insulator assembly is formed to the final shape and the conductors 4 are slightly crimped at points 4a adjacent to the insulators 5.

The insulator spacers 5 may be made of any insulating material, such as, synthetic porcelain, hard rubber, phenol or rosin condensation products, wax impregnated wood and the like. A sufficient number of spacers is employed to keep the loop antenna conductors properly spaced after they are threaded through the shield members l.

A rubber ring or grommet 6 is placed over the centrally disposed spacer. The assembled conductors 4 and spacers 5 are fed into one of the ends of each of the semicircular tubular members l, as shown in Fig. 4, and the ends of the conductors brought out of the opposite ends of these tubular members.

After the conductors 4 are placed into the tubes I, ends of these tubes are welded together and to the member I which forms the bottom and support of the loop and holds the two semicircular tubes I together. Selected ends of the conductors 4 are soldered together at 4a in such a manner that the looped conductors inside of the tubes I form a plurality of turns connected in series, shunt or series-shunt. The ends 4?) of the loop coil are brought out of the bottom of the member 1.

Pressure is applied to the loop casing in the direction of the arrows l3 to press the ends of the tube ends into the grommet 6 and make a water-tight joint. The loop is thus adapted for use in exposed places, such as, on aeroplanes, ships, automobiles and similar vehicles and vessels.

An insulation member I2 is fitted into the bottom of the member I and suitable slip-rings 9 and ID are mounted on the member. The leads 4!; are connected to these slip-rings as shown.

r Suitable brushes are employed with the slip-rings 9 and IE] for the purpose of connecting the loop to a signal receiver.

It will be readily seen, therefore, that according to the present invention, a novel shielded loop antenna has been provided that requires no auxiliary coupling means in order to main tain a weatherproof joint at the insulated point of the shield. Once the two tubes 1 have been pressed into the grommet or ring 8 and while in this condition welded together and to the mounting member I, no additional means is needed to keep the joints formed between grommet 6 and tubes l tight, since the rigidity of the completed shielding casing will maintain the edges of the tubes snugly against the sides of the ring or grommet 6. This not only facilitates manufacture but makes possible a shielded loop structure having none of the mechanical disadvantages inherent in structures employing bulky coupling members for effecting a weatherproof joint.

What I claim and desire to secure by Letters Patent of the United States is as follows:

1. The method of manufacturing a loop antenna having a metal shield, an insulating grommet and mounting means, which comprises forming two tubular shielding members into substantially semi-circular shape, placing the grommet over cut loop turns at some point intermediate their ends, inserting the cut loop turns into each tubular member with the grommet between two adjacent ends thereof, pressing the two ends into the grommet and holding said tubular members in this relation while uniting the two opposite ends of the tubular members together and to the mounting means.

2. The method of manufacturing loop antennas including the steps of cutting a plurality of turns of wire, spacing said turns from each other by insulation and arranging said turns side by side to form a cut ring-like member, threading said ring-like member through an insulation grommet and through a pair of substantially semi-circular tubular members one on each side of said insulation grommet, pressing adjacent ends of said tubular members into said grommet, maintaining them so pressed, rigidly connecting the opposite ends of said tubular members to each other to form a unitary shield, joining selected ends of said turns to form a desired inductance from said plurality of turns of wire, leading out the ends of said inductance, and uniting suitable mounting means to said shield.

3. The method of manufacturing loop antennas including the steps of threading a plurality of cut turns of substantially circular shape spaced from each other through an insulation grommet and through a pair of substantially semi-circular tubular members one on each side of said insulation grommet, pressing adjacent ends of said tubular members inward to force the ends of said members into said insulation grommet and form a weather-tight joint therebetween, joining the ends of. said tubular members remote from said grommet together to form a split ring antenna shield joining selected ends of said turns to form a continuous coil of the antenna and mounting said antenna shield member on an attachment fitting having contact members for said coil.

4. An antenna assembly comprising a tubular metallic shield, a loop antenna disposed therein, said shield being unitary and substantially circular having ends spaced apart to break the electrical continuity of the shield and a resilient insulating ring disposed between said ends and being under compression, said ring being retained under compression solely by the rigidity of said shield.

5. The combination with a loop antenna having spaced turns, of a metallic tubular shield enclosing said antenna and having spaced ends, discs of insulating material carried by said turns for maintaining the same in spaced relation, an insulating grommet of resilient material arranged over one of said discs, the ends of said tubular shield being embedded in said grommet to form a weatherproof union therewith, said union being maintained solely by the rigidity of said shield, independently of auxiliary fastening means.

LAWRENCE A. HYLAND. 

